Wafer Switch Contact Lubrication?

[jadney]

This question has bothered me for a long time:

What, if any, lubrication is appropriate for wafer switch contacts? I'm talking about those multiple position rotary switches that typically (but not always) have several wafers (switch sections) on a single shaft.

I'm comfortable with rather ordinary grease for the rotating shaft bearings, etc, but the contacts are different material and can't afford the insulation between contacts to be compromised.

I'm pretty sure Tek used to lube these with something in the old days, when you shipped scopes back to them for cleaning and recal. Yeah, I know, that was a LONG time ago. I think Tek even had lube kits that you could buy that contained suitable lubricants for different areas.

This is a general question, not related only to Tek scopes.

 

[Jeff Liebermann]

On Sat, 19 Sep 2015 21:01:25 -0700 (PDT), jadney <jadney@vwtype3.org>
wrote:

>What, if any, lubrication is appropriate for wafer switch contacts?

Caig Labs Cramolin
<http://store.caig.com/s.nl/ctype.KB/it.I/id.324/KB.215/.f>
<http://store.caig.com/s.nl/ctype.KB/it.I/id.316/KB.218/.f?category=3>

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Phil Allison]

jadney wrote:

This question has bothered me for a long time:

What, if any, lubrication is appropriate for wafer switch contacts?

** Switch contacts need no lubricant in order to work, after all, new switches are supplied without any applied.

Eventually, contacts may need cleaning which requires a hydrocarbon solvent ( but not Freon or Alcohol ) mixed with and a bit of light oil to protect worn metal surfaces.

If the contacts are accessible, you can * sparingly* apply the mixture with a small artist's brush - if not, then you have to rely on capillary action to get some solvent inside. Then you rotate the switch so it can clean itself.

The most effective and harmless products for the job are WD40 or CRC 2-26 both of which contain a mixture of Naptha and light mineral oil in a ratio of about 8:1.



..... Phil

 

[Chris Jones]

On 20/09/2015 14:01, jadney wrote:

This question has bothered me for a long time:

What, if any, lubrication is appropriate for wafer switch contacts? I'm talking about those multiple position rotary switches that typically (but not always) have several wafers (switch sections) on a single shaft.

I'm comfortable with rather ordinary grease for the rotating shaft bearings, etc, but the contacts are different material and can't afford the insulation between contacts to be compromised.

I'm pretty sure Tek used to lube these with something in the old days, when you shipped scopes back to them for cleaning and recal. Yeah, I know, that was a LONG time ago. I think Tek even had lube kits that you could buy that contained suitable lubricants for different areas.

This is a general question, not related only to Tek scopes.

Electrolube sell contact grease and contact oil. I have used these but I
don't really know if they are good as I have not done controlled
experiments. The MSDS lists some ingredients (including an anti-oxidant
iirc), in case you wish to research it. In the past I have found that
some of their aerosol cans tend to have quality problems e.g. leaking
from around the valve.

Some old fluke meters had service manuals which used to warn against
removing the grease from the rotary switch.

Chris

 

[Tim Schwartz]

On 9/20/2015 12:01 AM, jadney wrote:

This question has bothered me for a long time:

What, if any, lubrication is appropriate for wafer switch contacts? I'm talking about those multiple position rotary switches that typically (but not always) have several wafers (switch sections) on a single shaft.

I'm comfortable with rather ordinary grease for the rotating shaft bearings, etc, but the contacts are different material and can't afford the insulation between contacts to be compromised.

I'm pretty sure Tek used to lube these with something in the old days, when you shipped scopes back to them for cleaning and recal. Yeah, I know, that was a LONG time ago. I think Tek even had lube kits that you could buy that contained suitable lubricants for different areas.

This is a general question, not related only to Tek scopes.

I've used both Caig Labs Deoxit D5, and Mobil 1 5W30 synthetic oil. If
the switch is really clean, or if I've cleaned a silver plated switch
with cotton swabs and alcohol they I'll just use the oil. The 5W30 is
not a specifically 'better' weight, just the one I have on hand. (I do
not like things like WD40 on switches.) I've got switches I've cleaned
10+ years ago that are still fine.

Note: If AC power is on the wafer, then I'd suggest dry contacts.

Regards,
Tim
Bristol Electronics

 

[whit3rd]

On Saturday, September 19, 2015 at 9:01:41 PM UTC-7, jadney wrote:

This question has bothered me for a long time:

What, if any, lubrication is appropriate for wafer switch contacts?

No lubricant- the wiping action of the switch is supposed to displace material
and that applies to most 'lubricant' compounds. Any lubricant that took
the pressure and retained a film, would likely impede the electrical contact.

There IS a use for Cramolin 'DeOxit', or Tweak, or Stabilant-22 or other
contact enhancers, though, but it isn't for their lubricant properties.
It has nothing to do, either, with oxidation. It increases the contact
footprint by conducting across very narrow gaps.

The switch might have such a contact enhancer applied at the factory; you'd
never know it by inspection, unless the pink and blue stains I sometimes see
are indicators of some sort (for factory inspection purposes).